Modular batteries are batteries which comprise two or more battery cells or cell modules or cells. A common example of a device using a modular battery is a hand held flashlight which may use for example two C cells.
Recently, modular batteries have become important in many applications, including hybrid electric vehicles (“HEV”), plug-in hybrid electric vehicles (“PHEV”), and other applications. When used in HEV, PHEV, and other applications, in addition to being durable, safe and cost effective, modular batteries are required to deliver a great deal of power.
Applications of modular batteries, like the hand-held flashlight, require the use of multiple battery cells connected in series. However, the modular batteries for HEVs and PHEVs, for example, may differ from the modular C cells used in a common flashlight.
U.S. Pat. Nos. 5,552,243 and 5,393,617 disclose a bipolar electrochemical battery of stacked wafer cells. The wafer cells are electrically connected in series with the positive face of each cell contacting the negative face of the adjacent cell. The cell-to-cell contact may be enhanced by use of a conductive paste or cement. The stack assembly is held in compression. U.S. Pat. Nos. 5,552,243 and 5,393,617 are hereby incorporated by reference herein.